Apparatus for and method of case-hardening an arcuate member



Oct. 6, 1970 E. H. DEHN 3,532,333

APPARATUS FOR AND METHOD OF CASE-HARDENING AN ARCUATB MEMBER Filed Dec. 21, 1967 I 3 Sheets-Sheet l 33b 331' 37a I, 330

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. \RoSm ukm. x t RM. Ee n t mkm APPARATUS FOR AND METHOD OF CASE-HARDENING AN ARCUATE MEMBER Filed Dec. 21. 1967 E. H. DEHN Oct. 6, 1970 3 She ecs-Sheet 3 ITS/FA- Fm-AB m 0 m 7 T mm 5 Z r V Attorney United States Patent O 3,532,333 APPARATUS FOR AND METHOD OF CASE- HARDENING AN ARCUATE MEMBER Edward H. Dehn, Oil City, Pa., assignor to United States Steel Corporation, a corporation of Delaware Filed Dec. 21, 1967, Ser. No. 692,559 Int. Cl. CZld 1/66 U.S. Cl. 266-4 13 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the surface hardening of arcuate members and, more particularly, to an improved apparatus for and method of surface hardening arcuate members having a continuous surface. The apparatus has means for supporting and rotating the arcuate member at a predetermined velocity, and heating means adjacent the supported arcuate member for case-hardening the continuous surface with a minimum width of tempered overlap.

The improved method includes the steps of supporting and rotating slowly the arcuate member at a predetermined velocity, heating the continuous surface to provide a moving heated area on the continuous surface, which moving heated area is disposed at an angle with respect to a contact portion (between the arcuate member and its track) to maximize the ratio of the area of the contact portion to the area of the intersection of the tempered overlap and the contact portion, minimize the width of the heated area and the area of the tempered overlap and quench the heated area to case-harden the heated area.

BACKGROUND OF THE INVENTION Heretofore, arcuate members having a continuous surface provided with a contact portion, such as car wheels, brake wheels and the like, were case-hardened by heating the entire wheel (in a conventional gas, coal or oil fired furnace or in an induction heating coil) and then quenching the surface of the wheel which was to be case-hardened. The continuous surface of the wheel is the tread and sometimes a flange on the rim of the wheel. The contact portion is the moving substantially stragiht line contact between the rim of the wheel and the track upon which the rim rides. One disadvantage of the conventional method is the large electrical power and fuel requirements for heating such wheels. Further, the depth and location of the hardened case on the Wheel was difficult to control uniformly, often resulting in the undesirable hardening and embrittling of inner portions of the wheel extending from the rim into the core or web and sometimes into the hub of the wheel, thus producing a hard brittle web rather than a tough ductile web. In addition the diameter of the wheels which can be case-hardened is limited by the conventional apparatus.

Conventional heat-treating apparatus is shown in the following United States patents:

U.S. Patent No. Inventor Issue date 1,276,106 Pease et a1 Aug. 20, 1918 1,391,907.-. Schafier Sept. 27, 1921 1,697,068. Kenney Jan. 1, 1929 1,204,327. Kenney et aL.-. Mar. 5, 1929 2,068,913- Jan. 26, 1937 2,596,345. May 13, 1952 2,356,150. Denneen et a1 Aug. 22, 1944 2,398,0 Denneen et a1--- Apr. 9, 1946 2,521,699... Denneen et 91... Sept. 12, 1950 2,524, Denneen et a1--- Oct. 3, 1950 2,582,929. Gridley Jan. 15, 1952 2,749,423- Bisterfield. June 5, 1956 2,759,085. Van Iperen ug. 14, 1956 2,777,041. Dustman Jan. 8, 1957 2,785,263. Van Ipeien Mar. 12, 1957 2,810,054... Jones-.. Oct. 15, 1957 2,825,788... Loving"... Mar. 4, 1958 2,828,397... Emerson... Mar. 25, 1958 2,820,466... Wisharl: Jan. 21, 1958 2,857,154-.. nes Oct. 21, 1958 3,119,917 Dehn Jan. 28, 1964 OBJECTS OF THE INVENTION It is the general object of the present invention to avoid and overcome the foregoing and other difliculties of and objections to prior art practices by the provision of an improved apparatus for and method of case-hardening an arcuate member having a continuous surface provided with a contact portion, which method and apparatus:

(1) require a minimal power or fuel requirement to case-harden the arcuate member,

(2) provide uniform control of the depth of and the location of the hardened case on the arcuate member,

(3) are adapted to case-harden arcuate members of any diameter, and

(4) provide a tough ductile core in the arcuate member, which core is unaffected by the case-hardening process and is not undesirably hardened or embrittled.

BRIEF SUMMARY OF THE INVENTION The aforesaid objects of this invention, and other objects which will become apparent as the description proceeds, are achieved by providing improved apparatus for surface or case-hardening an arcuate member having a continuous surface provided with a contact portion and having means for supporting and rotating the arcuate member at a predetermined velocity, and heating means adjacent the supported arcuate member for case-hardening the continuous surface with a minimum width of tempered overlap. The heating means is generally contoured to provide a moving heated area on the continuous surface and is disposed at an angle with respect to the contact portion to maximize the ratio of the area of the contact portion to the area of the intersection of the tempered overlap and the contact portion. The width of the heated area and the tempered overlap area is minimized, and quenching means are connected to a fluid source and dis posed adjacent the heating means for quenching and casehardening the heated area.

The improved method includes the steps of supporting and rotating the arcuate member at a predetermined velocity, heating the continuous surface to provide a moving heated area on the continuous surface, which moving heated area is disposed at an angle with respect to the contact portion to maximize the ratio of the area of the contact portion to the area of the intersection of the tempered overlap and the contact portion, minimizing the width of the heated area and the tempered overlap area, and quenching the heated area to case-harden the heated area.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS For a better understanding of this invention reference should be had to the accompanying drawings, wherein like numerals of reference indicate similar parts throughout the several views and wherein:

FIG. 1 is a side elevational view partially in vertical section of the improved case-hardening apparatus and a wheel being case-hardened;

FIG. 2 is a perspective view of the wheel being casehardened and an induction heating means;

FIG. 3 is a side elevational view of the wheel being case-hardened and showing the heated area and the tempered overlap area;

FIG. 4 is a front view of the substantially straight line type of induction heating coil shown in FIGS. l-3;

FIGS. 4A, 4B are views similar to FIG. 4 of alternative embodiments of the induction heating coil;

FIG. 5 is a front view of a substantially straight line type of heating torch; and

FIG. 5A is a side elevational view of the heating torch shown in FIG. 5 and taken from the left side of FIG. 5 along the line 5A--5A of FIG. 5 in the direction of the arrows.

Although the principles of this invention are broadly applicable to case-hardening of arcuate members, this invention is particularly adapted for use in conjunction with the controlled low power induction heating or low fuel consumption type of heating of arcuate members to case-harden them and hence it has been so illustrated and will be so described.

DETAILED DESCRIPTION With specific reference to the form of this invention illustrated in the drawings, and referring particularly to FIG. 1, a surface hardening apparatus is indicated generally by the reference numeral 10.

This surface hardening apparatus is employed to surface or case-harden an arcuate member, such as a wheel 12 (FIGS. 13), having a continuous surface, suitably a rim 18 (FIGS. 1-3) of the wheel 12 having a tread 14 (FIGS. 1-3) and flange 16 (FIGS. 1-3). In addition, the wheel 12 has a core 20 (FIGS. 1, 2) and a hub 22 (FIGS. 1-3). The rim 18 is provided with a movable contact portion Zcp (FIG. 3), namely the substantially straight line contact between the rim 18 and the track (not shown) on which the wheel 12 rides.

For the purpose of supporting and rotating slowly the wheel 12 at a predetermined velocity V (FIGS. 1, 2), a table 26 (FIG. 1) carries a turntable 28 (FIG. I) mounted on a shaft 30 (FIG. 1) journaled in a bearing 32 (FIG. 1) in the table 26 and driven by a gear-reduction unit 34 (FIG. 1) and a motor 35 (FIG. 1).

Referring now to FIGS. 1, 2, a heating means, such as an induction heating apparatus 36, is disposed adjacent the supported rotating wheel 12 for heating the rim 18 above the critical temperature (as hereinafter explained) for the particular metal in the wheel 12 so that the rim 18 may be later quenched and case-hardened with a minimum width Wto of tempered overlap zone Zto (FIG. 3) as hereinafter described. The induction heating apparatus 36 has an induction heating coil 36a (FIGS. 2, 4) connected by leads 36b, 360 (FIG. 2) to a hollow block 37, FIG. 2, fluid cooled as by water or the like.

This fluid-cooled block 37 has two hollow halves 37a (FIG. 2) and 371) (FIG. 2) each provided with elongated mounting slots 370 (FIG. 2) to facilitate the mounting of the coil 36a adjacent the wheel 12. In order to electrically insulate the two halves 37a, 37b of the block 37 from each other and to integrate such blocks 37a, 37b, an insulating spacer 370! (FIG. 2) formed of a dielectric material, such as Bakelite or the like, is disposed therebetween and the half blocks 37a, 37b are mounted on an insulating block 37d (FIG. 2), suitably Bakelite or the like, by bolts 37:: extending through the insulating block 37a" and threadable into the half blocks 37a, 37b. Side mounting plates 37h, 37h (FIG. 2) are mounted on the half blocks 37a, 37b by bolts 37c (FIG. 2) and are insulated and spaced from their adjacent half blocks 37a, 3711 respectively by insulating spacers 37d (FIG. 2), insulating washers 376' (FIG. 2), and an insulating sleeve (not shown). Bakelite is the trade name of a dielectric material manufactured by Union Carbide Corporation, New York, NY.

Referring now to FIG. 1, each half block 37a, 37b is mounted on an individual terminal block 33a of bus bars 33!), 336 respectively by means of bolts 37e extending through the slots 37c (FIG. 2) and threading into threaded holes 33a in the terminal blocks 33a. The bus bars 33b, 330 in turn are integrated by a dielectric block 336, which block 332 is mounted on a bracket 37L by means of bolts 37:: extending through an insulating washer 33f, an insulating sleeve 33g in the bracket 37L, the dielectric block 330 and threading into the terminal blocks 33a. The bracket 37L is secured to the table 26 by bolts 37c and nuts 37 In order to electrically insulate the terminal blocks 33a from each other and also the bus bars 33b, 330 from each other, an insulating spacer 3311 is disposed therebetween. The bus bars 33b, 33c are connected by conventional means (not shown) to a power source, such as a transformer (not shown). In order to cool the bus bars 33b, 33c, half blocks 37a, 3712, etc., a fluid, such as water, flows from a fluid supply indicated by the legend FROM FLUID SUPPLY into channels 33i provided in the bus bars 33b, 33c and in the terminal blocks 33a; through connecting loops 33L to the half blocks 37a, 37b; and thence through the leads 36b, 360 to the coil 360. For the purpose of integrating the mid portions of the bus bars 33b, 330 insulating blocks 33m are secured by bolts 37:: which thread into nuts 3311 brazed to the channels 33i.

The coil 36a is generally contoured to the shape of the tread 14 and the flange 16, as shown in FIGS. 1, 2, to provide a heated area Zha (FIG. 3) on the tread 14 and flange 16. As shown in FIG. 1, the smaller radius tread 14 is spaced at a distance d from the coil 36a while the larger radius flange 16 is spaced a distance d from the coil 36a. The distance d is greater than the distance d The coil 36a is disposed at an angle B (FIG. 3) with respect to the contact portion Zcp to maximize the ratio of the area of the contact portion Zcp to the area of the tempered overlap Zto.

In order to minimize the Width W (FIG. 3) of the heated area Zha and the resultant tempered overlap area Zto, intensifying means, such as the intensifiers 38 (FIGS. 1, 2, 4) are mounted on the coil 36a. These intensifiers or flux concentrators 38 are formed of a ferromagnetic plastic, for example, powdered iron dispersed in plastic binders as disclosed in United States Pat. 2,777,041, issued ]an., 1957 to H. C. Dusttnan or of the type known as Ferrotron and manufactured by The Polymer Corporation, Reading, Pa.

The means utilized for quenching the heated area Zha is a quenching means, such as the quench head 40a (FIGS. 1, 2). This spray or quench head 40a is connected by a conduit 40c (FIGS. 1, 2) (attached to the side mounting plate 3711' on the fluid-cooled block 37, as by welding) and extending to a fluid supply, indicated by the legend FROM FLUID SUPPLY. The fluid employed in the quench head 40a may, for example, be water, oil

or a mixture of water and Aqua Quench, a water soluble, resinous material used as an additive for water quenching systems to provide a quenching rate between that of water and the fastest quenchable oil and manufactured by the E. F. Houghton & Company, Philadelphia, Pa. The quench head 40a is disposed a distance D (FIG. 2) from the coil 36a to provide a soaking zone or soaking time for the wheel 12 and is disposed below the coil 36a to prevent adverse cooling of the already heated portion of the rim 18 of the wheel 12.

For the purpose of cooling the intensifiers 38 on the coil 36a, spray heads 40b (FIGS. 1, 2) are directed at the intensifiers 38 and connected by lines 40d (FIGS. 1, 2) through a block 37g (FIGS. 1, 2) attached to the mounting plate 37a as by welding, to a line 40e leading to a fluid supply (indicated by the legend FROM FLUID SUPPLY) and suitably air, water or the like. The intensifiers 38 are cooled below a temperature in the range of about 450-500 F., the breakdown temperature, by a fine atomized mist from the spray heads 4%.

The fluid from the quenching head 40a and spray heads 40b is collected in a tray 39 (FIG. I) mounted by means of resilient spacers 39a (FIG. 1) on the table 26.

EXAMPLES If the wheel 12 is composed of a type 1050 steel having about 0.50% (by weight) carbon and 0.91% manganese, the coil 36a must raise the temperature of the moving heated area Zha (FIG. 3) above a temperature of about 1650 F. to properly austenitize the wheel 12. Prompt cooling by the quench head 40a below about 200 F. will provide a proper martensite content with a Rockwell hardness of about 62.

When a wheel 12 is formed, for example, of a modified type 4150 alloy steel having by weight a carbon content of about 0.55%, a manganese content of about 0.60%, a chromium content of about 1.03%, a molybdenum content of about 0.19% and a nickel content of about 0.36%, the coil 36a raises the moving heated area Zha (FIG. 3) above a temperature of about 1550 F. and upon selfquenching through the mass of the wheel 12 below about 450 F., a Rockwell hardness of about 55 is produced.

In the tempered overlap zone Zto (FIG. 3) the preheat beyond the heated zone Zha reheats the already casehardened rim 18, up to, for example, a temperature of about 600 F. where in the case of the type 1050 steel and type 4150 steel the respective hardnesses are reduced to about 48 Rockwell and about 51 Rockwell.

From a consideration of FIG. 3 it is apparent that by disposing the tempered overlap Zto at an angle B with respect to the contact portion Zcp, the ratio of the area of the contact portion Zcp to the area of the intersection AI (FIG. 3) of the tempered overlap zone Zto and the contact portion Zcp is maximized and Wear at the weak point (i.e. the intersection AI of the tempered overlap zone Zto and the contact portion Zcp) is minimized.

It has been found that the best results are obtained when the angle B is in the range of about to 80.

ALTERNATIVE EMBODIMENTS It will be understood by those skilled in the art that alternatively, as shown in FIGS. 4A, 4B, the induction heating coil may be arcuate convex as illustrated by the coil 36 (FIG. 4A) or arcuate concave as exemplified by the coil 36 (FIG. 4B). In FIGS. 5, 5A a gas-fired torch 36 is provided with intensifier means, such as divergent nozzle burners 46 to provide the minimized width W (FIG. 3) for the moving heated area Zha. The torch 36 is connected by lines 44a, 44b, 44c (FIG. 5) through the block 37g (or attached to a half block 37a or 37b) to a gas air supply indicated by the legend FROM GAS AIR SUPPLY. As shown in FIG. 5A, each burner 46 provides an overlapping heated area Zha (indicated by the overlapping dotted circles). This overlapping heated area Zha can also be produced by cylindrical or converging nozzle burners 46.

METHOD It will be understood from the above description that an improved method is also provided for surface hardening an arcuate member or wheel 12 (FIGS. 1-3) having a continuous surface or rim 18 provided with a contact portion Zcp (FIG. 3). This method includes the steps of supporting and slowly rotating the arcuate member or wheel 12 (FIG. 1) at a predetermined velocity (FIGS. 1, 2), heating the continuous surface 18 (FIGS. 2, 3, 5A) to provide a moving heated area Zha (FIG. 3) on the continuous surface 18, which moving heated area Zha is disposed at an angle B with respect to the contact portion Zcp to maximize the ratio of the area of the contact portion Zcp to the area of the intersection AI (FIG. 3) of the tempered overlap Zto and the contact portion Zcp, minimizing the width W of the heated area Zha and the width Wto (FIG. 3) of the tempered overlap area Zto, and quenching the heated area Zha to case-harden the heated area Zha.

SUMMARY OF THE ACHIEVEMENT OF THE OBJECTS OF THE INVENTION It will be recognized by those skilled in the art that the objects of this invention have been achieved by providing an improved apparatus 10 (FIGS. 1-4) for and an improved method of case-hardening an arcuate member 12 having a continuous surface 18 provided with a contact portion Zcp, which apparatus 10 and method require minimal power or fuel consumption to case-harden the arcuate member 12, provide uniform control of the depth and the location of the hardened case on the arcuate member 12, are adapted to case-harden arcuate members 12 of any diameter, and provide a tough ductile core 20 in the arcuate member 12, which core 20 is unaffected by the case-hardening process and is not undesirably hardened or embrittled.

While in accordance with the patent statutes preferred and alternative embodiments of this invention have been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or thereby.

I claim:

1. Apparatus for surface hardening an arcuate member having a continuous surface provided with a contact portion having an axis of rotation and having:

(a) means for supporting and slowly rotating said arcuate member at a predetermined velocity, and

(b) heating means adjacent said supported arcuate member for case-hardening said continuous surface with a minimum width of tempered overlap,

(1) said heating means being generally contoured to provide a moving heated area on said continuous surface and disposed at an acute angle with respect to said axis of rotation of said contact portion to maximize the ratio of the area of said contact portion to the area of the intersection of said tempered overlap and said contact portion,

(2) intensifier means on said heating means to minimize the width of said heated area and said tempered overlap area, and

(3) quenching means connected to a fluid source and disposed adjacent said heating means for quenching and case-hardening said heated area.

2. The apparatus recited in claim 1 wherein said heating means is an induction coil connected to a power source.

3. The apparatus recited in claim 1 wherein said heating means is a gas-fired torch connected to a gas-air source.

4. The apparatus recited in claim 2 wherein said intensi- 7 fier means on said induction coil minimizes the width of the magnetic field of said induction coil.

5. The apparatus recited in claim 3 wherein said intensifier means on said gas-fired torch is a nozzle burner.

6. The apparatus recited in claim 1 wherein said heating means is substantially straight.

7. The apparatus recited in claim 1 wherein said heating means is substantially arcuate convex with respect to a longitudinal axis of said heating means.

8. The apparatus recited in claim 1 wherein said heating means is substantially arcuate concave with respect to a longitudinal axis of said heating means.

9. A method for surface hardening an arcuate member having a continuous surface provided with a contact portion having an axis of rotation and including the steps of:

(a) supporting and slowly rotating said arcuate mem her at a predetermined velocity,

(b) heating said continuous surface to provide a moving heated area on said continuous surface and disposed at an acute angle with respect to said axis of rotation of said contact portion to maximize the ratio of the area of said contact portion to the area of the intersection of said tempered overlap and said contact portion,

(c) minimizing the width of said heated area and said tempered overlap area, and

(d) quenching said heated area to case-harden said heated area.

10. The method recited in 'claim 9 wherein said continuous surface is induction heated.

11. The method recited in claim 9 wherein said continuous surface is torch heated.

12. The apparatus recited in claim 1 wherein said quenching means is a quench head disposed in spaCed relation ahead of said heating means.

13. The apparatus recited in claim 1 and having a spray head for cooling said heating means.

References Cited UNITED STATES PATENTS 2,085,790 7/ 1937 Campbell 266-5 2,414,362 1/ 1947 Denneen et a1 266-4 2,424,816 7/1947 Groven et a1. 219-1059 2,477,029 7/1949 Wood 266-4 X 2,512,893 6/1950 Gehr 2664 2,882,191 4/1959 Van Swaal 266-4 X FOREIGN PATENTS 225,333 1923 Great Britain.

I. SPENCER OVERHOLSER, Primary Examiner R. S. ANNEAR, Assistant Examiner U.S. Cl. X.R. 148150, 151, 153 

